package cache

import (
	"sync"
	"time"
)

type entry struct {
	value   string
	expires time.Time
}

type Cache struct {
	ttl    time.Duration
	mu     sync.RWMutex
	values map[string]entry
}

func New(ttl time.Duration) *Cache {
	if ttl <= 0 {
		ttl = time.Hour
	}
	return &Cache{
		ttl:    ttl,
		values: make(map[string]entry),
	}
}

func (c *Cache) Get(key string) (string, bool) {
	c.mu.RLock()
	e, ok := c.values[key]
	c.mu.RUnlock()
	if !ok {
		return "", false
	}
	if time.Now().After(e.expires) {
		c.mu.Lock()
		delete(c.values, key)
		c.mu.Unlock()
		return "", false
	}
	return e.value, true
}

func (c *Cache) Set(key string, value string) {
	c.mu.Lock()
	c.values[key] = entry{
		value:   value,
		expires: time.Now().Add(c.ttl),
	}
	c.mu.Unlock()
}

func (c *Cache) ClearExpired() int {
	now := time.Now()
	c.mu.Lock()
	removed := 0
	for k, v := range c.values {
		if now.After(v.expires) {
			delete(c.values, k)
			removed++
		}
	}
	c.mu.Unlock()
	return removed
}

func (c *Cache) TTL() time.Duration {
	return c.ttl
}